Three types of projects will be conducted: 1. Effect of inhibitors of cerebral protein synthesis on memory storage in mice. Attempts will be made to evaluate the role of side effects in the amnesia produced by administration of cerebral protein synthesis inhibitors including cycloheximide and anisomycin on learning and memory in mice. 2. Studies of neurophysiological and biochemical correlates of "neuronal plasticity" in Aplysia. Mechanisms of "frequency facilitation" and postetanic potentiation at an identified unitary monosynaptic cholinergic synapse which impinges on the parabolic burster cell (R-15) in the abdominal ganglion of Aplysia Californica will be evaluated by neurophysiological and pharmacological means. In addition, the identity and subcellular localization of a phosphoprotein obtained from the abdominal ganglion of Aplysia Californica which is abundantly phosphorylated in response to octopamine, serotonin or cyclic AMP will be determined. 3. Studies of interneuronal and other intercellular interactions. A carbohydrate binding protein from Dictyostelium discoideum which is synthesized abundantly as the cells become cohesive and which may mediate intercellular adhesion will be studied further. In addition, a high molecular weight glycoprotein from developing chick brain which is assayed by its ability to agglutinate formalized chick erythrocytes will be further purified, characterized, and its subcellular localization determined after raising antibodies to the purified protein.